In f(R,T) = R + F(T) gravity, nonlinear F makes the averaged modified term differ from F at averaged T, invalidating the common unity-ratio assumption and giving dust nonzero proper pressure.
Does the growth of structure affect our dynamical models of the universe? The averaging, backreaction and fitting problems in cosmology
6 Pith papers cite this work, alongside 212 external citations. Polarity classification is still indexing.
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abstract
Structure occurs over a vast range of scales in the universe. Our large-scale cosmological models are coarse-grained representations of what exists, which have much less structure than there really is. An important problem for cosmology is determining the influence the small-scale structure in the universe has on its large-scale dynamics and observations. Is there a significant, general relativistic, backreaction effect from averaging over structure? One issue is whether the process of smoothing over structure can contribute to an acceleration term and so alter the apparent value of the cosmological constant. If this is not the case, are there other aspects of concordance cosmology that are affected by backreaction effects? Despite much progress, this 'averaging problem' is still unanswered, but it cannot be ignored in an era of precision cosmology.
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A covariant zoom-in perturbation theory framework resolves geodesic breakdown via hierarchical matter horizons, producing an effective energy-momentum tensor whose backreaction explains flat galaxy rotation curves without dark matter.
A shear-free locally FLRW lattice framework for single-field inflation captures spatially varying expansion, curvature corrections, and nonlinear δN observables at a fraction of the cost of full numerical relativity.
The fraction of AbacusSummit cosmologies excluded at 3σ by small-scale clustering multipoles drops from 81% to 25% when moving from fixed HOD parameters to broad marginalization over the five-parameter HOD model.
Gaia quasar proper motions show a significant quadrupole signal matching an axisymmetric Bianchi I anisotropy model, but the amplitude does not increase with redshift as the model requires and the inferred local shear exceeds expectations.
Embedding a static Schwarzschild interior into a GCT-FLRW exterior via Israel junction conditions produces a geometric consistency condition that coincides with the GCT background equations.
citing papers explorer
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Cosmological Averaging in Nonminimally Coupled Gravity
In f(R,T) = R + F(T) gravity, nonlinear F makes the averaged modified term differ from F at averaged T, invalidating the common unity-ratio assumption and giving dust nonzero proper pressure.
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Cosmological zoom-in perturbation theory as a consistent beyond point-particle approximation framework
A covariant zoom-in perturbation theory framework resolves geodesic breakdown via hierarchical matter horizons, producing an effective energy-momentum tensor whose backreaction explains flat galaxy rotation curves without dark matter.
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Nonlinear Lattice Framework for Inflation: Bridging stochastic inflation and the $\delta{N}$ formalism
A shear-free locally FLRW lattice framework for single-field inflation captures spatially varying expansion, curvature corrections, and nonlinear δN observables at a fraction of the cost of full numerical relativity.
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Bounding the Effect of HOD Assumptions on Small-Scale Clustering Constraints
The fraction of AbacusSummit cosmologies excluded at 3σ by small-scale clustering multipoles drops from 81% to 25% when moving from fixed HOD parameters to broad marginalization over the five-parameter HOD model.
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Mapping the Universe as a Bianchi I cosmology with Gaia data
Gaia quasar proper motions show a significant quadrupole signal matching an axisymmetric Bianchi I anisotropy model, but the amplitude does not increase with redshift as the model requires and the inferred local shear exceeds expectations.
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Geometric Matching of Local Static Regions in Cosmological Spacetimes with an Evolving Lapse
Embedding a static Schwarzschild interior into a GCT-FLRW exterior via Israel junction conditions produces a geometric consistency condition that coincides with the GCT background equations.